MAX1679 Datasheet, PDF (5/12 Pages) Maxim Integrated Products – Single-Cell Li Battery Charger for Current-Limited Supply

Single-Cell Li+ Battery Charger
for Current-Limited Supply
Typical Operating Characteristics
(VIN = V _CHG = +10V, VBATT = +4.2V, THERM = 10kΩ to GND, TA = +25°C, unless otherwise noted.)
1.0200
1.0150
TIMER PERIOD vs.
AMBIENT TEMPERATURE
NORMALIZED TO +25°C
1.0100
1.0050
1.0000
0.9950
0.9900
-40 -20
0 20 40 60
TEMPERATURE (°C)
80 100
NORMALIZED BATT REGULATION VOLTAGE
vs. TEMPERATURE
1.0015
NORMALIZED TO +25°C
1.0010
1.0005
1.0000
0.9995
0.9990
0.9985
0.9980
0.9975
-40 -20
0 20 40 60
TEMPERATURE (°C)
80 100
PRECHARGE CURRENT
vs. INPUT VOLTAGE
6.0
5.8
5.6
V_BATT = 0V
5.4
5.2
V_BATT = 2V
5.0
4.8
4.6
V_BATT = 4.1V
4.4
4.2
4.0
5
10
15
20
25
V_IN (V)
Pin Description
PIN NAME
FUNCTION
1
IN
Input Voltage from Current-Limited Voltage Source (+22V max). Bypass to GND with a 0.1µF capacitor. The
cell charging current is set by the current limit of the external power supply.
2
GATE
Gate Drive for External PMOS Pass Element. The PMOS device should have a V_GS threshold of 2.5V or
less. See Selecting External Components.
Charge Status Indication. CHG is an open-drain, current-limited N-channel MOSFET suitable for directly dri-
3
CHG ving an LED. Connect a pull-up resistor to BATT to generate a logic-level signal. See Table 2 for CHG out-
put states.
4
TSEL Maximum Total Charge-Time Selection. See Table 3 for timer options.
Battery Regulation Voltage Adjustment. Bypass to GND with a 1000pF capacitor. Connect a resistor from
5
ADJ
ADJ to GND to reduce the nominal +4.200V regulation setpoint. See Adjusting the Battery Regulation
Voltage.
6
GND
Ground. See Layout Guidelines for information on system grounding. Connect the battery’s negative termi-
nal to GND.
Thermistor Temperature-Sensor Input. Connect a thermistor from THERM to GND to prequalify the cell tem-
7
THERM
perature for fast-charge. Drive THERM high (> +1.4V) during Done or Fault states to reset the MAX1679 and
reinitiate the charging sequence. Replace the thermistor with a 10kΩ resistor if temperature sensing is not
required.
8
BATT
Cell Voltage Monitor Input, Trickle-Charge Output, and MAX1679 Power Source. Connect BATT to the posi-
tive terminal of a single Li+ cell. Bypass BATT with a capacitor to ground (1.5µF per amp of charge current).
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